WO2012067449A2

WO2012067449A2 - Anode active material for lithium secondary battery, method for manufacturing same, and lithium secondary battery including same

Info

Publication number: WO2012067449A2
Application number: PCT/KR2011/008809
Authority: WO
Inventors: 선양국; 김원기; 오승민
Original assignee: 한양대학교 산학협력단
Priority date: 2010-11-17
Filing date: 2011-11-17
Publication date: 2012-05-24
Also published as: WO2012067449A3

Abstract

Provided are an anode active material for lithium secondary batteries and a lithium secondary battery including the anode active material for lithium secondary batteries, the anode active material for lithium secondary batteries comprising a core including a compound represented by chemical formula 1 and a shell including a compound represented by chemical formula 2, wherein the substance comprising the core and the substance comprising the shell are different.

Description

【Specification】

[Name of invention]

Cathode active material for lithium secondary battery, method for manufacturing same and lithium secondary battery comprising same

Technical Field

The present invention relates to a cathode active material for a lithium secondary battery, a method of manufacturing the same, and a lithium secondary battery including the same.

Background Art

<2> A battery generates electric power by using an electrochemical reaction material for the positive electrode and the negative electrode. A typical example of such a battery is a lithium secondary battery that generates electric energy by a change in chemical potential when lithium ions are inserted and desorbed from a positive electrode and a negative electrode.

The lithium secondary battery is manufactured by using a material capable of reversible insertion and detachment of lithium ions as a positive electrode active material and a negative electrode active material, and filling an organic electrolyte or a polymer electrolyte between the positive electrode and the negative electrode.

As a negative electrode active material of a lithium secondary battery, various types of carbon-based materials including artificial graphite, natural graphite, hard carbon, etc., into which lithium may be inserted and detached, are used.

A lithium composite metal compound is used as a cathode active material of a <5> lithium secondary battery, and examples thereof include LiCo0 ₂ , LiMn ₂ 0 _4> LiNi0 ₂ , LiNi ₁ - _x Co _x 0 ₂ (0 <x <l), and LiMn0 Bimetallic oxides such as ₂ and LiFePO ₄ have been studied.

[Detailed Description of the Invention]

[Technical problem]

One embodiment provides a cathode active material for a lithium secondary battery having excellent output characteristics, capacity characteristics, thermal stability, and lifetime characteristics.

Another embodiment is to provide a method of manufacturing the cathode active material for a lithium secondary battery.

Another embodiment is to provide a lithium secondary battery including the cathode active material for the lithium secondary battery.

Technical Solution

<9> A cathode active material for a rechargeable lithium battery according to one embodiment may include a core including a compound represented by Formula 1 below; And a shell containing a compound represented by the formula (2) And the material composition of the core and the material composition of the shell are different from each other.

<ιο> [Formula 1]

<ii> Li _x iMlyiM2 _z iP0 ₄ -wiEwi

<12> [Formula 2]

<i3> Li _x2 M3 _y2 M4 _Z 2P04-w2Ew2

In Formulas 1 and 2,

<i5> Ml, M2, M3, and M4 are the same or ivory to each other, and each independently Ni, Co,

Mn, Fe, Na, Mg, Ca, Ti, V, Cr, Cu, Zn, Ge, Sr, Ag, Ba, Zr, Nb, Mo, Al, Ga, B, and combinations thereof, ..

<i6> E is selected from the group consisting of F, S and combinations thereof,

<17> 0 <xl <l.l, 0 <yl <l, 0 <zl <l, 0 <xl + yl + zl <2,

<18> 0 <wl <0.5,

<19> 0 <x2 <l.l, 0 <y2≤l, 0 <z2 <l, 0 <x2 + y2 + z2 <2,

<20> 0 <w2 <0.5.

The Ml and M3 may be the same material, and the M2 and M4 may be the same material, and xl = x2, yl <y2 and zl> z2. At this time, the Ml and the M3 may be selected from the group consisting of Fe, Co, Ni, Mn, and combinations thereof, wherein M2 and M4 are Mn, Ni, Co, Fe and combinations thereof Can be selected from the military.

In the cathode active material for a lithium secondary battery, Ml and M3 may be different materials. In addition, the M2 and the M4 may be different materials.

The Ml and M2 may be different from each other, and the core may have a structure in which the concentration of Ml increases and the concentration of M2 decreases as the core moves away from the center of the core. In this case, Ml may be selected from the group consisting of Fe, Co, Ni, Mn, and combinations thereof, and M2 may be selected from the group consisting of Mn, Ni, Co, Fe, and a combination thereof.

<24>^" The core may have a diameter of about 5 μνι to about 20.

The Μ3 and Μ4 are different from each other, and the shell may have a structure in which the concentration of the Μ3 increases and the concentration of the Μ4 decreases as the shell moves away from the interface between the core and the shell. , Co, Ni, Mn and combinations thereof, wherein M4 is Mn ,. Ni, Co, Fe, and combinations thereof. The shell may have a thickness of about 100 nm to about 5 / m.

<27> The lithium secondary battery positive electrode active material may be ^'further include a carbon coating layer on the surface of the shell.

The carbon coating layer may have a thickness of about 10 nm to about 200 nm.

The cathode active material for a lithium secondary battery may further include an intermediate layer between the core and the shell, and the intermediate layer may include a compound represented by the following Chemical Formula 3. In this case, the material composition of the intermediate layer may be different from the material composition of the core and the material composition of the shell.

<30> [Formula 3]

<3i>^" Li _X3 M5 _y3 M6 _z3 P0 ₄ - _W 3E _w3 <32> In Chemical Formula 3,

M5 and M6 are the same or ivory, and each independently Ni, Co, Mn, Fe,

Na, Mg, Ca, Ti, V, Cr, Cu, Zn, Ge, Sr, Ag, Ba, Zr, Nb, Mo, Al, Ga, B, and combinations thereof,

E is selected from the group consisting of F, S and combinations thereof,

<35> 0 <x3 <ll , 0 <y3 <l, 0 <ζ3 <1, 0 <x3 + y3 + z3 <2 , _and.

<36> 0 <w3 <0.5.

The Ml, M3 and M5 may be the same material, the M2, M4 and M6 may be the same material, xl = x2 = x3, yl <y3 <y2 and zl> z3> z2. Can be. At this time, the Ml, the M3 and the M5 may be selected from the group consisting of Fe, Co, Ni, Μη and combinations thereof, wherein the M2, M4 and M6 are Mn, Ni, Co, Fe And combinations thereof may be selected from the group.

In the cathode active material for a lithium secondary battery, Ml, M3, and M5 may be different materials from each other. In addition, the M2, the M4 and the M6 may be different materials from each other.

The M5 and M6 may be different from each other, and the additional layer may have a structure in which the concentration of M5 increases and the concentration of M6 decreases as the distance from the core increases, wherein M5 represents Fe, Co, and Ni. , Mn, and combinations thereof, and ^' M6 may be selected from the group consisting of Mn, Ni, Co, Fe, and combinations thereof.

The intermediate layer may have a thickness of about 100 nm to about 24.

The positive active material for a lithium secondary battery may have a diameter of about 5 kPa to about 25 and a tap density of about 1 g / cm ³ to about 2 g / cm ³ . According to another embodiment, a method of manufacturing a cathode active material for a lithium secondary battery may include a Ml source and a M2 source. And mixing the phosphoric acid source to form a core precursor; Mixing the core precursor with an M3 source, an M4 source and a phosphoric acid source to form a core shell shell precursor comprising a shell precursor formed on the surface of the core precursor; Heat treating the core one-shell precursor to form a core-shell composite; And the steps of mixing and firing the core-shell composite with a lithium source.

The description of Ml, M2, M3, and M4 is as described above.

The Ml source, the M2 source, the M3 source and the M4 source are respectively

Sulfur oxides, nitrates, acetates, phosphates, chlorides, oxalates, fluorides, carbonates or combinations of Ml, M2, M3 and M4.

The phosphoric acid source is phosphoric acid (¾P0 ₄ ), diammonium phosphate ((NH ₄ ) ₂ HP0 ₄ ), ammonium phosphate trihydrate ((NH ₄ ) ₃ P0 ₄ .3H ₂ 0), metaphosphoric acid), orthophosphoric acid

(orthophosphoric acid), ammonium dihydrogen phosphate (NH ₄ H ₂ P0 ₄ ) or a combination thereof.

The source of lithium is lithium phosphite (Li ₃ P0 ₄ ), lithium nitrate (LiN0 ₃ ), lithium acetate (LiC¾C00H), lithium carbonate (Li ₂ C0 ₃ ), lithium hydroxide (LiOH), Lithium dihydrogen phosphate (Li¾PO ₄ ) or a combination thereof.

The heat treatment may be carried out at a silver degree of about 300 ^° C to about 70 C C.

The firing may be carried out at a silver degree of about 600 ^° C to about 800 ^° C.

The method of manufacturing the cathode active material for a lithium secondary battery may further include forming a carbon coating layer on a surface of the core-shell composite after forming the core shell composite.

In the method of manufacturing a cathode active material for a lithium secondary battery, after forming the core precursor, mixing the core precursor with an M5 source, an M6 source, and a phosphoric acid source to form an intermediate layer precursor on the surface of the core precursor. It may further include.

<5i> The description of the M5 and the M6 is as described above.

The M5 source and the M6 source may include sulfur oxides, nitrates, acetates, phosphates, chlorides, oxalates, fluorides, carbonates, or combinations thereof, of M5 and M6, respectively. The description of the phosphoric acid source is as described above.

In another embodiment, a method of manufacturing a cathode active material for a rechargeable lithium battery is Ml. Mixing the source and the M2 source to form a core precursor; Mixing the core precursor 'with an M3 source and an M4 source to form a core-shell precursor comprising a shell precursor formed on the surface of the core precursor; And mixing and firing the core-shell precursor with a lithium source and a phosphoric acid source.

The Ml, the M2, the M3, the M4, the Ml source, the M2 source, the M3 source, the M4 source, phosphoric acid source, lithium source and firing have been described above.

The method of manufacturing the cathode active material for a lithium secondary battery may further include forming a carbon coating layer on a surface of the core-shell precursor after the forming of the core-shell precursor.

The method of manufacturing a cathode active material for a lithium secondary battery further includes, after forming the core precursor, mixing the core precursor with an M5 source and an M6 source to form an intermediate layer precursor on the surface of the core precursor. can do.

The description of the M5, the M6, the M5 source, and the M6 source is as described above.

According to another embodiment, a lithium secondary battery including a cathode including the cathode active material, an anode including an anode active material, and an electrolyte is provided.

Advantageous Effects

_<59>. The cathode active material for a rechargeable lithium battery according to one embodiment may have a core-shell structure, and thus may have excellent output characteristics, capacity characteristics, thermal stability, and lifetime characteristics. [Brief Description of Drawings] ^'

1 is a view schematically illustrating a structure of a lithium secondary battery according to an embodiment.

FIG. 2 is a scanning electron microscope (SEM) photograph at a magnification of 3,000 times of a portion of the core-shell precursor prepared in Example 1. FIG.

FIG. 3 is a scanning electron microscope (SEM) photograph at a magnification of 30,000 times of a portion of the core-shell precursor prepared in Example 1. FIG.

4 is energy dispersive X-ray (EDX) analysis data of the core-shell precursor prepared in Example 1. FIG.

FIG. 5 is an enlarged view of 12, 000 times a portion of the core-shell precursor prepared in Example 2. FIG.

^• Four electron microscopy (SEM) pictures.

FIG. 6 shows a part of the positive electrode active material for a lithium secondary battery prepared in Example 2 It is a scanning electron microscope (SEM) photograph magnified 15, 000 times.

FIG. 7 is a scanning electron microscope (SEM) photograph at a magnification of 4, 000 times of a portion of the active material precursor prepared in Comparative Example 2.

FIG. 8 is a scanning electron microscope (SEM) photograph at a magnification of 30,000 times a part of the active material precursor prepared in Comparative Example 2. FIG.

9 is an energy dispersive X-ray (EDX) analysis data of the active material precursor prepared in Comparative Example 2.

FIG. 10 is a scanning electron microscope of a cross section of the core-shell precursor prepared in Example 3. FIG.

(SEM) picture.

FIG. 11 is energy dispersive X-ray (EDX) analysis data for point A of FIG. 10, and FIG. 12 is energy dispersive X-ray (EDX) analysis data for point B of FIG. 10.

FIG. 13 is a scanning electron microscope of a cross section of an active material precursor prepared in Comparative Example 4

(SEM) picture.

FIG. 14 is energetic distributed X-ray (EDX) analysis data for point C of FIG. 13, and FIG. 15 is energy distributed X-ray (EDX) analysis data for point D of FIG.

FIG. 16 is a one-time charge and discharge whale of the coin half sal prepared in Example 4. FIG.

FIG. 17 is a one-layer discharge graph of the coin half cell prepared in Comparative Example 7. ·

FIG. 18 is a single layer discharge graph of coin half cells prepared in Example 5 and Comparative Example 8. FIG.

19 is a one-time layer discharge graph of the coin half cell prepared in Example 6. FIG.

20 is a one-time charge / discharge graph of the coin half cell prepared in Comparative Example 9.

FIG. 21 is a graph illustrating changes in discharge capacity during 50 cycle layer discharge of the coin half cells prepared in Example 4 and Comparative Example 7. FIG.

FIG. 22 is a graph illustrating changes in discharge capacity during 50-cycle layer discharge of coin half cells prepared in Example 5 and Comparative Example 8. FIG.

FIG. 23 is a DSC graph of the coin half cell of Example 4, Comparative Example 6, and Comparative Example 7. FIG.

[Best form for implementation of the invention]

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. However, this is presented as an example, by which the present invention is not limited and the present invention is defined only by the scope of the claims to be described later.

In the drawings, thicknesses may be enlarged to clearly express various layers and areas. Burned out. Like reference numerals designate like parts throughout the specification.

When parts of layers, membranes, areas, plates, etc. are said to be "on" another part, this includes not only the other part "right on" but also another part in the middle. On the contrary, when a part is "just above" another part, there is no other part in the middle.

According to one embodiment, the positive electrode active material for a lithium secondary battery includes a core including a compound represented by Formula 1 below; And it includes a shell containing a compound represented by the formula (2). At this time, the material composition of the core and the material composition of the shell is different from each other / ^' , in the case of the following formula 1 and 2, M1 = M3, yl = y2, M2 = M4, zl = z2 and wl = w2 And there is no case where M2 = M3, zl = y2, M1 = M4, yl = z2, and wl = w2.

<85> [Formula 1]

<86> Li _x iMl _yl M2 _z iP0 ₄ - _w iE _wl

<87> [Formula 2]

<88> Li _x2 M3 _y 2M4 _Z 2P04- _w2 E _i v2

In Chemical Formulas 1 and 2,

Ml, M2, M3, and M4 are the same or different from each other, and each independently Ni, Co,

Mn, Fe, Na, Mg, Ca, Ti, V, Cr, Cu, Zn, Ge, Sr, Ag, Ba, Zr, Nb, Mo, Al, Ga, B, and combinations thereof, Specifically, Ni, Co, Mn, Fe, Mg,

• may be selected from the group consisting of Al, Zn, Mo and combinations thereof.

E is selected from the group consisting of F, S, and combinations thereof, and specifically may be F.

<92> 0 <xl <l.l, 0 <yl <l, 0 <zl <l, 0 <xl + yl + zl <2, specifically 0.9 <xl <

1.1, 0 <yl <l, 0 <zl <l, 0.9 <xl + yl + zl <2.

0 <wl <0.5, specifically, 0 <wl <0.3.

<94> 0 <x2 <l.l, 0 <y2 <l, 0 <ζ2 <1, 0 <x2 + y2 + z2 <2, specifically 0.9 <x2 <

1.1, 0 <y2 <l, 0 <ζ2 <1, 0.9 <x2 + y2 + z2 <2.

0 <w2 <0.5, and specifically, 0 <w2 <0.3.

The cathode active material for a lithium secondary battery may include the core and the shell, thereby complex and effectively improving various physical properties of the lithium secondary battery. For example, in the case of using a material having high voltage characteristics and high energy density as the core, and using a material having excellent thermal stability and life characteristics as the shell, the lithium secondary The lithium secondary battery comprising a cathode active material for battery output ^{characteristics:} it is possible to at the same time as improving the capacity and characteristics, improve myeoljeok reliability and lifetime characteristics. However, the present invention is not limited thereto, and the material constituting the core and the material constituting the shell may be the same or different from each other, and may include materials having various electrochemical and physical pools, respectively. . As a result, the cathode active material for a lithium secondary battery has an advantage of effectively achieving various desired physical properties.

The core and the cathode active material for the lithium secondary battery may be spherical, elliptical, or a combination thereof, but are not limited thereto.

As an example, Ml and M3 may be the same material, and M2 and M4 may be the same material, where xl = x2, yl <y2 and zl> z2 may be satisfied. In this case, the core and the shell include the same material, but the concentration of the materials included in each of the core and the shell, that is, the material composition is different. As a result, the disadvantages of each material composition, such as low oxidation / reduction potential, low discharge capacity, poor lifetime characteristics, poor thermal stability, can be overcome by forming core-shell structures with other material compositions. The positive electrode active material for a lithium secondary battery that can effectively exhibit only the advantages of the composition of the material can be made.

At this time, the Ml and the M3 may be selected from the group consisting of Fe, Co, Ni, Mn, and combinations thereof, wherein the M2 and M4 is made of Mn, Ni, Co, Fe and combinations thereof It may be selected from the group, but is not limited thereto. The superiority of the high voltage characteristics is in the order of Ni>Co>Mn> Fe, and the superiority of the thermal stability and the lifetime characteristics is in the order of Fe>Co>Mn> Ni. Therefore, by properly selecting the materials included in the core and shell in consideration of these characteristics, it is possible to effectively improve the high voltage characteristics, thermal stability and life characteristics. For example, the combination of (M1, M2) may be (Fe, Mn), (Co, Ni), (Ni, Co), (Mn.Fe), (Ni, Fe), (Ni, Co), and also The combination of (M3, M4) may also be (Fe, Mn), (Co, Ni), (Ni, Co), (Mn.Fe), (Ni, Fe), (Ni, Co), but is not limited thereto. It is not. Specifically, Ml and M3 may be Fe, yl = 0, M2 and M4 may be Mn, and z2 = 0. In this case, the core can be a lithium-manganese-phosphate composite to improve high voltage characteristics and increase the energy density, and the shell can be a lithium-iron-phosphate composite to express excellent thermal stability and lifetime characteristics. have. As a result, the positive electrode active material for a lithium secondary battery including such a core and a shell may have excellent thermal stability and lifespan while having excellent output characteristics and capacity characteristics. <ιοι> As another example, Ml and M3 may be different materials, and M2 And M4 may be different materials from each other. Specifically, the M1, M2, M3 and M4 may be different from each other. At this time, the M1 to M4 may be independently selected from the group consisting of Fe, Co, Ni, Mn, and combinations thereof, but is not limited thereto. Specifically, the combination of (M1, M2), which is a substance included in the core, is (Ni, Co), (Νΐ, Μη), (Co, Mn), (Ni, Co), (Ni, Mn), (Co _' Mn), and the combination of (M3, M4), which is a material included in the shell, is (Fe.Mn), (Fe, Co), (Fe, Ni), (Mn'Fe), (Co, Fe ), (Ni.Fe) and the like, but is not limited thereto. In this case, the core can improve the high voltage characteristics and increase the energy density, and the shell can improve the thermal stability and lifespan characteristics. Therefore, the positive electrode active material for a lithium secondary battery including the core and the shell as described above may have excellent output characteristics, capacity characteristics, thermal stability, and lifetime characteristics.

Meanwhile, in the cathode active material for a lithium secondary battery, the Ml and M2 are different from each other, and the core has a structure in which the concentration of Ml increases and the concentration of M2 decreases as the core moves away from the center of the core. have. The change in concentration may be continuous. However, the present invention is not limited thereto, and the change in concentration may be discontinuous, and in this case, the core may be formed in a multilayer structure. Of course, such a structure can be applied not only when the material constituting the core and the material constituting the shell are the same, but also when the material constituting the core and the material constituting the shell are different. In this case, Ml may be selected from the group consisting of Fe, Co, Ni, Mn, and combinations thereof, and M2 may be selected from the group consisting of Mn, Ni, Co, Fe, and combinations thereof. It is not limited. In the core, when the concentration of Ml and M2 is changed as described above, it is possible to form a stable crystal structure without causing a sudden change in the material composition in the core, each of the different materials constituting the core To compensate for the disadvantages of the electrochemical properties, it is possible to express the advantages of the respective electrochemical properties of the different materials constituting the core. In addition, it is possible to prevent or alleviate the generation of impurity phase by preventing a sudden difference in material composition with the shell in the portion adjacent to the shell.

The core may have a diameter of about 5 to about 20. When the diameter of the core is within the above range, it is possible to easily form a core-shell composite, and to effectively improve the electrochemical properties. Specifically, the core may have a diameter of about 7 to about 15 .

In the cathode active material for a lithium secondary battery, the M3 and M4 are different from each other, The shell may have a structure in which the concentration of M3 increases and the concentration of M4 decreases as the shell moves away from an interface between the core and the shell. The change in concentration may be continuous. However, the present invention is not limited thereto, and the change in concentration may be discontinuous, and in this case, the shell may be formed in a multilayer structure. Of course, such a structure can be applied not only when the material constituting the core and the material constituting the shell are the same, but also when the material constituting the core and the material constituting the shell are different. In this case, M3 may be selected from the group consisting of Fe, Co, Ni, Mn, and combinations thereof, and M4 may be selected from the group consisting of Mn, Ni, Co, Fe, and combinations thereof, but is not limited thereto. It doesn't happen. In the shell, when the concentration of M3 and M4 is changed as described above, it is possible to form a stable crystal structure by not changing the material composition in the shell abruptly, and each of the different materials constituting the shell To compensate for the disadvantages of the electrochemical properties, it is possible to express the advantages of the respective electrochemical properties of the different materials constituting the shell. In addition, it is possible to prevent or mitigate the generation of impurity phase by preventing a sudden difference in material composition with the core in the portion adjacent to the core.

The shell may have a thickness of about 100 nm to about 5. When the thickness of the shell is within the above range, the core-shell composite can be formed while maintaining the morphology of the core-shell composite, and the electrochemical characteristic of the cathode active material for a lithium secondary battery including the same by effectively supplementing the electrochemical characteristics of the core Can be effectively improved. Specifically, the shell may have a thickness of about 200 nm to about 3.

The cathode active material for a lithium secondary battery may further include a carbon coating layer on a surface of the shell. The cathode active material for a lithium secondary battery may further include the carbon coating layer, thereby improving electrical conductivity and having excellent electrochemical properties.

The carbon coating layer may have a thickness of about 10 nm to about 200 nm. When the thickness of the carbon coating layer is within the above range, it is possible to effectively improve the electrical conductivity, whereby the positive electrode active material for a lithium secondary battery comprising the same may have excellent electrochemical properties. Specifically, the carbon coating layer may have a thickness of about 15 nm to about 100 nm. ·

In the positive electrode active material for a lithium secondary battery, a core and a shell are described separately, but are not limited thereto. The materials included in the core and the shell are the same, and the materials included in the core and the shell are the same. When distributed with a continuous concentration gradient, the positive electrode active material for a lithium secondary battery is between the core and the shell The boundaries may be separated and exist in the form of one particle.

The cathode active material for a lithium secondary battery may further include an intermediate layer between the core and the shell, and the material composition of the intermediate layer is different from the material composition of the core and the material composition of the shell. In this case, the intermediate layer may include a compound represented by Formula 3 below. ^.

[Formula 3]

Li _x3 M5 _y3 M6 _z3 P0 ₄ - _w3 E _w3

In Chemical Formula 3,

M5 and M6 are the same or different from each other, and each independently Ni, Co, Mn, Fe, Na, Mg, Ca, Ti, V, Cr, Cu, Zn, Ge, Sr, Ag, Ba, Zr, Nb, Mo , Al, Ga, B and combinations thereof, and may be selected from the group consisting of Ni, Co, Mn, Fe, Mg, Al, Zn, Mo and combinations thereof.

E is selected from the group consisting of F, S and combinations thereof, and specifically may be F.

0 <x3 <ll, 0 <y3 <l, 0 <ζ3 <1, 0 <x3 + y3 + z3 <2, specifically 0.9 <x3 <1.1, 0.1 <y3 <0.9, 0.1 <z3 <0.9, 1.1 3+ 3 + 23 <2.

0 <w3 ≦ 0.5 and specifically 0 ≦ w3 <0.3.

As an example, the Ml, the M3 and the M5 may be the same material, the M2, the M4 and the M6 may be the same material, xl = x2 = x3, yl <y3 <y2 and zl> z3> z2 may be satisfied. In this case, the core, the intermediate layer and the shell include the same material, but the concentration of the materials contained in each of the core, the intermediate layer and the shell, that is, the material composition is different. When the intermediate layer is present, and the intermediate layer has the same composition as the above, it is possible to prevent or alleviate the generation of blemishes, which may occur due to the sharp difference in the composition of the core and the shell, and the sudden phase boundary region does not appear. The crystal structure can be stabilized.

At this time, the Ml, the M3 and the. M5 may be selected from the group consisting of Fe, Co, Ni, Mn, and combinations thereof, and M2, M4 and M6 may be selected from the group consisting of Mn, Ni, Co, Fe, and combinations thereof. It is not limited to this. For example, the combination of (M1, M2) may be (Fe, Mn), (Co, Ni), (Ni, Co), (Mn, Fe), (Ni, Fe), (Ni.Co), and the like. The combination of (M3, M4) may be (Fe, Mn), (Co, Ni), (Ni, Co), (Mn.Fe), (Ni, Fe), (Ni, Co), etc. The combination of M5, M6) may also be (Fe, Mn), (Co.Ni), (Ni, Co), (Mn, Fe), (Ni, Fe), (Ni, Co). Specifically, Ml, M3 and M5 may be Fe, yl = 0, M2, M4, and M6 may be Mn, and z2 = 0. In this case, the core may be a lithium-manganese-phosphate composite to improve high voltage characteristics and increase energy density, and the thickening layer may be a lithium-iron-manganese-phosphate composite to form and rapidly form the core and the shell. One difference can be alleviated, and the shell can be a lithium-iron-phosphate composite to exhibit excellent thermal stability and lifespan characteristics. As a result, the cathode active material for a lithium secondary battery including such a core, an intermediate layer, and a shell may have a stable crystal structure, have excellent output characteristics and capacity characteristics, and may have excellent thermal stability and lifetime characteristics.

As another example, Ml, M3 and M5 may be different materials from each other, and M2, M4 and M6 may be materials different from each other. In this case, Ml to M6 may be independently selected from the group consisting of Fe, Co, Ni, Mn, and combinations thereof, but is not limited thereto. Specifically, the combination of (M1, M2), which is a material included in the core, may be (Ni, Co), (Νΐ, Μη), etc., and the combination of (Μ5.Μ6), which is a material included in the intermediate layer, may be (Co , Mn), (Mn, Co) and the like, and the combination of (M3, M4), which is a material included in the shell may be (Mn, Fe), (Co.Fe) and the like, but is not limited thereto. In this case, the core may improve high voltage characteristics and increase energy density, and the shell may improve thermal stability and lifespan characteristics. The intermediate layer may complement the electrochemical properties of the core and the shell. Therefore, the positive electrode active material for a lithium secondary battery including the core, the intermediate layer, and the shell may have excellent output characteristics, capacity characteristics, thermal stability, and lifespan characteristics.

<i2i> Meanwhile, in the cathode active material for a lithium secondary battery, M5 and M6 may be different from each other, and the intermediate layer may have a structure in which the concentration of M5 increases and the concentration of M6 decreases as the distance from the core increases. The change in concentration may be continuous. However, the present invention is not limited thereto, and the change in concentration may be continuous. In this case, the intermediate layer may be formed in a multilayer structure. Of course, such a structure is not only when the material constituting the core, the material constituting the shell and the material constituting the intermediate layer are the same, but also the material constituting the core, the material constituting the shell, and the intermediate layer constituting the intermediate layer. It can be applied even when the materials are different. In this case, the M5 may be selected from the group consisting of Fe, Co, Ni, Mn, and combinations thereof, and the M6 may be selected from the group consisting of Mn, Ni, Co, Fe, and a combination thereof. It is not limited to this. In the intermediate insect, the concentration change of M5 and M6 is the same as above. In this case, it is possible to form a stable crystal structure by preventing a sudden change in the material composition in the intermediate layer, to compensate for the shortcomings of the respective electrochemical characteristics of the different materials constituting the intermediate layer, and to constitute each other The advantages of each of the electrochemical properties of different materials can be compounded. In addition, it is possible to prevent or mitigate the generation of impurity phases by preventing a sudden difference in material composition from the core in the portion adjacent to the core and a sudden difference in material composition from the shell in the portion adjacent to the core. have.

The intermediate layer may have a thickness of about 100 nm to about 24. When the thickness of the intermediate layer is within this range, the core and can be ^"effectively prevented to ease the formation of the impurity that may be caused by an abrupt difference in the composition of the shell, it does not show a sharp phase boundary region stabilizing the crystal structure effectively can do. Specifically, the intermediate layer may have a thickness of about 1 / m to about 20.

In the positive electrode active material for a lithium secondary battery, a core, an intermediate layer, and a shell have been described separately, but are not limited thereto. The materials included in the core, the intermediate layer, and the shell are the same, and the core and the When the materials included in the intermediate layer and the shell are distributed with a continuous concentration gradient, the positive electrode active material for the lithium secondary battery is present in the form of one particle without a boundary between the core, the intermediate layer, and the shell. It may be.

Or more, but described with respect to various examples of the lithium secondary battery positive electrode active material according to one embodiment, but is not limited thereto.

The cathode active material for a lithium secondary battery may have a diameter of about 5 / m to about 25. When the diameter of the positive electrode active material for a lithium secondary battery is within the above range, the tap density may be excellent and the energy density may be effectively improved. Specifically, the cathode active material for a lithium secondary battery may have a diameter of about 5 μια to about 15.

The cathode active material for a lithium secondary battery may have a tap density of about 1 g / cm ³ to about 2 g / cm ³ . When the tap density of the cathode active material for a lithium secondary battery is within the above range, the energy density may be effectively improved. Specifically, the cathode active material for a lithium secondary battery may have a tap density of about 1.2 g / cm ³ to about 1.7 g / cm ³ , and more specifically, about 1.5 g / cm ³ to about 1,7 g / cm ³ . It may have a tap density. In another embodiment, a method of manufacturing a cathode active material for a rechargeable lithium battery includes mixing a Ml source, an M2 source, and a phosphoric acid source to form a core precursor; remind Mixing the core precursor with an M3 source, an M4 source, and a phosphoric acid source to form a core-shell precursor comprising a shell precursor formed on the surface of the core precursor; Heat treating the core-shell precursor to form a core-shell composite; And mixing and firing the core-shell composite with a lithium source. Unless otherwise described below, the description of the Ml, M2, M3 and M4 is as described above.

The Ml source, the M2 source, the M3 source and the M4 source are respectively

Sulfur oxides, nitrates, acetates, hydroxides, chlorides, oxalates, fluorides, carbonates or combinations of Ml, M2, M3 and M4.

The phosphoric acid source is phosphoric acid (H ₃ P0 ₄ ), diammonium phosphate ((NH ₄ ) ₂ HP0 ₄ ), ammonium phosphate trihydrate ((NH ₄ ) ₃ P0 ₄ · 3¾0), metaphosphoric acid acid), orthophosphoric acid

In the method of manufacturing the cathode active material for a lithium secondary battery, the core precursor and the shell precursor may be formed in the form of phosphate, oxalate, carbonate, hydroxide, or a combination thereof. Specifically, the core precursor and the shell precursor are each phosphate _. It may be formed in the form of a hydroxide, or a combination thereof.

When the core-shell precursor is heat-treated, the core-shell composite may be formed by removing moisture and residual organics from the core-shell precursor.

In the step of heat-treating the core shell shell precursor to form a core-shell composite, the heat treatment may be performed for about 1 hour to about 20 hours at a temperature of about 300 ^° C to about 700 ^° C. When the heat treatment is performed under the above conditions, the core-shell composite can be easily formed by effectively removing moisture and residual organic matter from the core-shell precursor, and also improving the crystallinity of the core-shell composite formed. The electrochemical properties of the positive electrode active material for a lithium secondary battery formed therefrom can be effectively improved. Specifically, the heat treatment can be performed at about 400 ^° C. to about 650 ^° C. for about 5 hours to about 15 hours. have.

The heat gain rate during the heat treatment may be about 1 ^° C./min to about 10 t / min. When the temperature increase rate is within the above range, the core-shell composite formed may have uniform crystallinity, thereby effectively forming the positive electrode active material for an olivine-type lithium secondary battery without generating an impurity phase. Specifically, the temperature increase rate during the heat treatment may be about 2C / min to about 5 ^° C / min. The lithium source may be lithium phosphate (Li ₃ P0 ₄ ), lithium nitrate (UN0 ₃ ), lithium acetate (LiC¾C00H), lithium carbonate (Li ₂ C0 ₃ ), lithium hydroxide (LiOH), lithium die Hydrogen phosphate (LiH ₂ P0 ₄ ) or combinations thereof, but is not limited thereto. The description of the phosphoric acid source is as described above. The core-shell composite and the lithium source may be mixed in a molar ratio of about 1: 0.8 to about 1: 1.2. When the molar ratio of the mixed core-shell composite and the lithium source is within the above range, the positive electrode active material for an olivine-based lithium secondary battery can be effectively formed in a stable structure, and does not produce a pure water phase, so that the positive electrode active material for a lithium secondary battery is excellent in electrical It may have chemical properties. Specifically, the core-shell composite and the lithium source may be mixed in a molar ratio of about 1: 0.9 to about 1: 1.1.

After mixing the lithium source with the core-shell composite, in the calcining step, the calcining may be performed at about 600 ^° C. to about 800 ^° C. for about 5 hours to about 20 hours. When the firing is performed under the above conditions, the crystallinity of the positive electrode active material for a lithium secondary battery to be formed may be improved and no impurities may be generated, thereby obtaining a cathode active material for a lithium secondary battery having excellent electrochemical properties. Specifically, the firing may be performed for about 10 hours to about 15 hours at a temperature of about 650 ^° C to about 750 ^° C.

<137> temperature-rising rate at the time of the calcination may be C / min from about It / min to about 10 ^°. When the temperature increase rate is within the above range, it is possible to improve the crystallinity of the positive electrode active material for a lithium secondary battery to be formed and not generate an impurity phase, thereby obtaining a positive electrode active material for a lithium secondary battery having excellent electrochemical characteristics. Specifically, the temperature increase rate during the firing may be about 2 ° C / min to about 5 ^° C / min.

The method of manufacturing the cathode active material for a lithium secondary battery may further include forming a carbon coating layer on a surface of the core-shell composite body after the forming of the core-shell composite. Specifically, the carbon coating layer comprises a carbon source such as pitch carbon, sucrose, glucose, polyvinyl alcohol, polypy, cellulose, acetylene black, super-p, and the like. After mixing with, it may be formed through a calcination step.

In addition, in the forming of the core precursor, the forming of the core-shell precursor, or a combination thereof, the core precursor, the core— Assist carbon in shell precursors or combinations thereof You can also wear. In this case, the electrical conductivity of the positive electrode active material for a lithium secondary battery formed can be improved _. have.

On the other hand, the method for producing the positive electrode active material for a lithium secondary battery is described in the above _. After forming the core precursor, the method may further include mixing the core precursor with an M5 source, an M6 source, and a phosphoric acid source to form an interlayer precursor on the surface of the core precursor. The intermediate layer precursor is then formed through the heat treatment and firing step to form an intermediate layer. Unless otherwise described below, the description of M5 and M6 is as described above.

<i4i> The interlayer precursor is an M5 source and an M6 source, and a phosphoric acid source, including sulfur oxides, nitrates, acetates, phosphates, chlorides, oxalates, fluorides, carbonates or combinations thereof, respectively, of M5 and M6. It may be formed by mixing and reacting with the core precursor, but is not limited thereto. The description of the phosphoric acid source is as described above.

The interlayer precursor may be formed in the form of phosphate, oxalate, carbonate, hydroxide, or a combination thereof. Specifically, the interlayer precursor may be formed in the form of phosphate, hydroxide, or a combination thereof.

According to another embodiment, a method of manufacturing a cathode active material for a lithium lithium battery is Ml.

Mixing the source and the M2 source to form a core precursor; Mixing the core precursor with an M3 source and an M4 source to form a core-shell precursor comprising a shell precursor formed on the surface of the core precursor; And mixing and firing the core-shell precursor with a lithium source and a phosphoric acid source. .

Unless stated otherwise, descriptions of the Ml, M2, M3, M4, Ml source, M2 source, M3 source, M4 source, phosphoric acid source, and lithium source are the same as described above.

In the method of manufacturing the positive electrode active material for a lithium secondary battery, the core precursor and the shell precursor may be formed in the form of phosphate, oxalate, carbonate, hydroxide, or a combination thereof. Specifically, the core precursor and the shell precursor may be formed in the form of oxalate, carbonate or a combination thereof, respectively.

In the step of mixing and firing the core-shell precursor with a lithium source and a phosphoric acid source, the core-shell precursor and the lithium source may be mixed in a molar ratio of about 1: 0.8 to about 1: 1.2. When the molar ratio of the compatible core-shell precursor and the lithium source is within the above range, the positive electrode active material for the olivine-based lithium secondary battery is effectively in a stable structure. ^'Can be formed with, it does not generate a phase impurities the cathode active material for a lithium secondary battery can have excellent electrochemical ^properties, can. Specifically, the core-shell precursor and the lithium source may be mixed in a molar ratio of 먁 1: 0.9 to about 1: 1.1.

After mixing a lithium source and a phosphoric acid source with the core-shell precursor, in the firing step, the firing may be performed at a temperature of about 600 ^° C. to about 800 ^° C. for about 5 hours to about 20 hours. Can be. When the firing is performed under the above conditions, the crystallinity of the positive electrode active material for a lithium secondary battery to be formed can be improved and an impurity phase is not generated, thereby obtaining a positive electrode active material for a lithium secondary battery having excellent electrochemical properties. Specifically, the firing may be performed at a temperature of about 650 ^° C to about 750 ^° C for about 10 hours to about 15 ^· hours.

In the firing, the temperature increase rate may be about 1 ^° C./minute to about 10 ^° C./minute. Temperature rise rate

^■ Within the above range, it is possible to improve the crystallinity of the positive electrode active material for a lithium secondary battery to be formed and not to produce an impurity phase, thereby obtaining a positive electrode active material for a lithium secondary battery having excellent electrochemical properties. Specifically, the firing rate during the firing may be about 2 ° C / min to about 5 ^° C / min.

The method of manufacturing the cathode active material for a lithium secondary battery may further include forming a carbon coating layer on a surface of the core-shell precursor after forming the core-shell precursor. Specifically, the carbon coating layer is pitch carbon, sucrose, glucose, polyvinyl alcohol, polypy, cellulose, acetylene block, super-pi

A super-p raw carbon source can be mixed with the core-shell precursor and then formed through a calcination step.

In addition, the core precursor and the core- may be further mixed with each other when the carbon precursor is formed, the core-shell precursor is formed, or a combination thereof is performed. Carbon may be introduced into the shell precursor or a combination thereof. In this case, the electrical conductivity of the cathode active material for a lithium secondary battery formed may be improved.

The method of manufacturing a cathode active material for a lithium secondary battery further includes, after forming the core precursor, mixing the core precursor with an M5 source and an M6 source to form an intermediate layer precursor on the surface of the core precursor. can do. The intermediate layer precursor is then formed into an intermediate layer through a firing step. Unless otherwise described below, the description of the M5 and M6 is as described above.

The interlayer precursors are sulfur oxides, nitride oxides, acetates of M5 and M6, Containing phosphates, chlorides, oxalates, fluorides, carbonates or combinations thereof

M5 source and M6 source may be formed by mixing and reacting with the core precursor-but is not limited thereto.

The interlayer precursor may be formed in the form of phosphate, oxalate, carbonate, hydroxide, or a combination thereof. Specifically, the interlayer precursor may be formed in the form of oxalate, carbonate, or a combination thereof.

The manufacturing method of the positive electrode active material for a lithium secondary battery is general in the art such as using a thickening agent, a complexing agent, for example, an aqueous solution of ammonia, a pH regulator, for example, an aqueous alkali solution providing a hydroxyl group, a heat treatment atmosphere, and the like. Is omitted.

According to the above process, a cathode active material for a rechargeable lithium battery according to one embodiment may be manufactured.

The positive electrode active material for a lithium secondary battery may be usefully used for a positive electrode of an electrochemical cell such as a lithium secondary battery. The lithium secondary battery includes a cathode and an electrolyte including a cathode active material together with the cathode.

The positive electrode includes a positive electrode current collector and a positive electrode active material layer formed on the positive electrode current collector.

The positive electrode active material layer also includes a binder and a conductive material.

The binder adheres positively to the positive electrode active material particles, and also adheres the positive electrode active material to the positive electrode current collector, and typical examples thereof include polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, di Acetyl salose, polyvinyl chloride, carboxylated polyvinylchloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinylpyridone, polyurethane, polytetrafluoroethylene, polyvinylidene pullo Ride, polyethylene, polypropylene, styrene-butadiene rubber, acrylic styrene-butadiene rubber, epoxy resin, nylon and the like may be used, but is not limited thereto.

The conductive material is used to impart conductivity to the electrode, and any battery can be used as long as it is an electronic conductive material without causing chemical change in the battery, and examples thereof include natural smoke, artificial graphite, carbon black, and acetylene. Metal powders such as black, Ketjen black, carbon fiber, copper, nickel, aluminum, silver, and metal fibers may be used, and conductive materials such as polyphenylene derivatives may be used alone or in combination of one or more thereof. .

<i6i> A1 may be used as the cathode current collector, but is not limited thereto. The negative electrode includes a negative electrode current collector and a negative electrode active material layer formed on the negative electrode current collector, and the negative electrode active material layer is _. It includes a negative electrode active material.

Lithium silver is reversibly inserted into the anode active material. And desorbable materials, lithium metals, alloys of lithium metals, materials capable of doping and undoping lithium, or transition metal oxides.

As a material capable of reversibly inserting and detaching lithium ions, any carbon-based negative electrode active material generally used in a lithium ion secondary battery may be used, and representative examples thereof include crystalline carbon, A combination of amorphous carbon or idol may be used. Examples of the crystalline carbon include amorphous, plate and lean pieces.

(flake), ^■ it can include graphite, such as ⁱ spherical or fibrous natural graphite or artificial graphite, and examples of the amorphous carbon are soft carbon (soft carbon: the low-temperature co-fired carbon) or hard carbon (hard carbon), meso Face pitch carbide, fired coke, and the like.

As the alloy of the lithium metal, lithium and Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr,

Alloys with metals of Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al or Sn can be used. Examples of the material capable of doping and undoping lithium include Si, Si0 _x (0 <x <2), and Si—M alloys (wherein M is an alkali metal alkaline earth metal, a group 13 to 16 element, and a transition). Metal, rare earth elements or combinations thereof, not Si), Sn, Sn0 ₂ , Sn_M (wherein M is an alkali metal, an alkali earth metal, a group 13 to 16 element, a transition metal, a rare earth element, or a combination thereof, Sn is not used), and at least one of these materials may be used in combination with Si0 ₂ . Examples of the element M include Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe , Pb, Ru, 0s, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Ti, Ge, P, As, Sb, Bi, S , Se, Te, Po or a combination thereof. ^'

Examples of the transition metal oxide include vanadium oxide, lithium vanadium oxide, and the like.

The negative electrode active material layer may also include a binder and optionally further include a conductive material.

The binder adheres the negative electrode active material particles to each other well, and also adheres the negative electrode active material to the negative electrode current collector. Examples of the binder include polyvinyl alcohol, carboxymethyl salose, hydroxypropyl salose, Polyvinylchloride, carboxylated Polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polvinylpyridone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoro. Id, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon, etc. may be used, but is not limited thereto.

The conductive material is used to impart conductivity to the electrode, and may be used as long as it is an electronic conductive material without causing chemical change in the battery. For example, natural alum, artificial graphite, carbon black, and acetylene black. , Ketjen black, carbon-based material of carbon core floating; Metal materials such as metal powder or metal fibers such as copper, nickel, aluminum and silver; Conductive polymers such as polyphenylene derivatives; Or an electroconductive material containing these mixture can be used.

As the negative electrode current collector, copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, or a combination thereof may be used.

The positive electrode and the negative electrode are each prepared by mixing an active material, a conductive material and a binder in a solvent to prepare an active material layer composition, and applying the composition to a current collector. Since such an electrode manufacturing method is well known in the art, detailed description thereof will be omitted. The solvent may be N-methylpyrrolidone, but is not limited thereto.

As the electrolyte layered on the lithium secondary battery, a non-aqueous electrolyte or a known solid electrolyte may be used, and a lithium salt may be used.

Examples of the solvent of the non-aqueous electrolyte include chain carbonates such as cyclic carbonates such as ethylene carbonate, diethylene carbonate, propylene carbonate, butylene carbonate, and vinylene carbonate, dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate. , Methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, esters such as y-butyrolactone, 1,2-dimethicethane, 1, 2-dieoxyethane, tetrahydrofuran Ethers such as 1,2-dioxane and 2-methyltetrahydrofuran, nitriles of acetonitrile, amides such as dimethylformamide, and the like can be used, but are not limited thereto. Itdi thereof alone or can be used a plurality of crude were combined. In particular, a mixed solvent of cyclic carbonate and chain carbonate may be used.

As the electrolyte, polymer electrolytes such as polyethylene oxide and polyacrylonitrile can be used. Gel-like polymer electrolytes impregnated with vaginal electrolytes or inorganic solid electrolytes such as Lil and Li ₃ N may be used, but are not limited thereto.

In this case, the lithium salt is LiPF ₆ , LiBF ₄₎ LiSbF ₆ , ^' LiAsF ₆ , LiC10 ₄ , LiCF ₃ S0 ₃ ,

^. Li (CF ₃ S0 ₂ ) ₂ N, LiC ₄ F ₉ S0 ₃₎ LiSbF ₆₎ LiA10 ₄ , LiA10 ₂ , LiAlCl ₄₎ LiCl and may be selected from the group consisting of Li I, but is not limited thereto.

Depending on the type of the lithium secondary battery, a separator may exist between the positive electrode and the negative electrode. The separator may be polyethylene, polypropylene, polyvinylidene fluoride, or a multilayer film of two or more thereof. It is a matter of course that a mixed multilayer film such as a polypropylene two-layer separator, a polyethylene / polypropylene / polyethylene three-layer separator, and a polypropylene / polyethylene / polypropylene three-layer separator may be used.

Lithium secondary batteries may be classified into lithium silver batteries, lithium silver polymer batteries, and lithium polymer batteries according to the type of separator and electrolyte used, and may be classified into cylindrical type, rectangular type, coin type, pouch type, and the like. It can be divided into bulk type and thin film type according to the size. The structure and manufacturing method of these batteries are widely known in the art, so detailed description thereof is omitted.

FIG. 1 schematically shows a structure of a lithium secondary battery according to one embodiment.

As shown in FIG. 1, the lithium secondary battery 100 includes a negative electrode 112; An anode 114 positioned opposite the cathode 112; A separator (113) disposed between the cathode (112) and the anode (114); A battery container 120 including an electrolyte (not shown) for impregnating the negative electrode 112, the positive electrode 114, and the separator 113; And an encapsulation member 140 encapsulating the battery container 120. The shape of the lithium secondary battery according to one embodiment is not particularly limited, and any shape such as a cylindrical type, a coin type, a pouch type, and the like may be possible as long as it can operate as a battery.

[Form for implementation of invention]

<180> Example

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the following Examples and Comparative Examples are for illustrative purposes only and are not intended to limit the present invention.

Example 1 Preparation of the Cathode Active Material for a Lithium Secondary Battery

<183> 4 L continuous stirred tank reactor (CSTR) (capacity MnS0 ₄ · 5H ₂ 0, H ₃ P0 ₄ and NH ₄ 0H were added at a molar ratio of 3: 2 to ₄ L, and the output of the rotary motor was greater than 90 W and reacted at a pH.7 condition. At this time. MnSCV-5¾0 was used to a molar concentration of 2.2 M. The internal temperature of the reaction vessel was stirred at 1000 rpm while maintaining at 55 ^° C. Stirred for 12 hours to prepare a micro-sized spherical core precursor Mn ₃ (P0 ₄ ) ₂ · xH ₂ 0.

Subsequently, after stopping the addition of MnS0 ₄ '5H ₂ 0, FeS0 ₄ · 7¾0 was added to a molar concentration of 2.2 M and stirred, and Fe ₃ (P0 ₄ ) ₂ · xH was added to the surface of the core precursor. forming a precursor of a shell ₂₀ and a core-shell precursor was prepared.

Subsequently, the core-shell precursor was filtered by filtration with a vacuum pump, and then dried at 70 ^° C. for 24 hours in a vacuum atmosphere.

<186> Manganese phosphate by heat treatment ^at 550 ^° C for 15 hours

An iron phosphate complex was obtained.

Subsequently, pitch carbon was mixed at 2 parts by weight with respect to 100 parts by weight of the manganese phosphate-iron phosphate complex to the manganese phosphate-iron phosphate composite.

Subsequently, the manganese phosphate-iron phosphate complex is mixed with lithium phosphate (Li ₃ P0 ₄ ).

Mixed at a molar ratio of 1: 1, the temperature of 5 ^° C./min is raised to 70 CTC at a rate, and then fired for 15 hours, thereby forming an olivine-type LiMnP0 ₄ (core) -LiFeP0 ₄ (shell) structure including a carbon coating layer. A positive electrode active material for a lithium secondary battery having was obtained.

Example 2 Fabrication of Positive Electrode Active Material for Lithium Secondary Battery

<i90> 4L continuous stirred tank half unggi (CSTR) and stirred a shot at the (capacity 4L, the output of more than 90W rotary motor) fills the 2L and H ₃ P0 ₄ 650 mL.

<i9i> Mn (N0 ₃ ) ₂ · 4¾0 and Fe (N¾) ₃ · 9¾0 were mixed in a molar ratio of 85:15 in another beaker, ethane was dissolved in 1 L, and then charged into the 4 L continuous stirred tank reactor (CSTR). do. This was followed by stirring at 1000 rpm while maintaining the internal temperature of the 4L continuous stirred tank reactor (CSTR) at 40 ^° C. After stirring for 5 hours, the micro-spherical spherical core precursor Mn ₀ . ₈₅ Fe ₀ . ₁₅ P0 ₄ - ₂ 0 was prepared.

Subsequently, the obtained core precursor is dispersed again in a 4L continuous stirred tank reaction vessel (CSTR). Subsequently, Fe (N0 ₃ ) ₃ · 9¾0 was added to 1M concentration and NH ₄ 0H was added thereto. It was added and stirred to maintain a pH of 2 to the surface of the core precursor FeP0 ₄ . A core-shell precursor was prepared by forming a shell precursor of x¾0.

The core-shell precursor was then filtered by filtration with a vacuum pump and then dried for 24 hours at 70 ^° C. under vacuum.

Then, heat treatment ^at 500 ^° C. for 1 hour in an atmosphere of manganese iron phosphate

An iron phosphate complex was obtained.

Next, pitch carbon was mixed at 2 parts by weight with respect to 100 parts by weight of the manganese iron phosphate-iron phosphate complex and stirred.

Subsequently, the manganese iron phosphate-iron phosphate complex is lithium carbonate (Li ₂ C0 ₃ ).

And a molar ratio of 1: 1, and heated to 700 ^° C at a temperature increase rate of 5 ^° C / min, and then fired for 15 hours, the olivine-type LiMn ₀ containing a carbon coating layer. ₈₅ Fe ₀ . ₁₅ P0 ₄ (core)

A positive electrode active material for a lithium secondary battery having a LiFePO ₄ (shell) structure was obtained.

Example 3 Preparation of Positive Electrode Active Material for Lithium Secondary Battery

<198> 4 L continuous stirred tank reactor (continuous stirred t nk reactor, CSTR) (capacity

4L, the output of the rotary motor more than 90W) NiS0 ₄ · 6H ₂ 0, H ₃ P0 ₄ and NH ₄ 0H was added in a molar ratio of 3: 2: 6 and reacted at pH 7 conditions. The NiS0 ₄ - the 6¾0 was used so that the molar concentration of 2.2 M. The internal silver degree of the reaction was stirred at 1000 rpm while maintaining at 55 ^° C. After stirring for 12 hours, a micro-sized spherical core precursor Ni ₃ (P0 ₄ ) ₂ · x¾0 was synthesized.

<199> was then stop the infusion of NiS0 _₄ .6¾0,) 30 ₄ 'by a 7¾0 added and stirred such that the molar concentration of 2.2 M, the surface of the core precursor of _{_{_{Co 3 (P0 4) 2 ·}}} x¾0 The shell precursor was formed to prepare a core-shell precursor.

Subsequently, the active material precursor was filtered by filtration with a vacuum pump, and then dried at 70 ^° C. for 24 hours under a vacuum atmosphere.

Then, nickel phosphate was heat-treated ^at 550 ^° C. for 10 hours under a reducing atmosphere.

A cobalt phosphate complex was obtained.

Next, the nickel phosphate is mixed with 5 parts by weight of pitch carbon and stirred with respect to 100 parts by weight of the nickel phosphate-cobalt phosphate composite to the nickel phosphate-cobalt phosphate composite. Carbon coating on the surface of cobalt phosphate composites Formed.

Subsequently, the nickel phosphate-cobalt phosphate composite having the carbon coating layer formed thereon was mixed with lithium phosphate (Li ₃ P0 ₄ ) in a molar ratio of 1: 1, and the temperature was increased to 750 at a temperature increase rate of 5 ^° C./minute.

After heating up to ^° C, firing was carried out for 10 hours to obtain a positive electrode active material for a lithium secondary battery having an euribin type LiNiP0 ₄ (core) -LiCoP0 ₄ (shell) structure.

Example 4: Fabrication of a Lithium Secondary Battery

The super-active material and the conductive material for the lithium secondary battery prepared in Example 1 were super-

Polyvinylidene fluoride (PVdF) was mixed with P and a binder in a weight ratio of 85: 7.5: 7.5, respectively, to prepare a positive electrode active material layer composition. The positive electrode active material layer composition was uniformly coated on a 20-thick aluminum foil, and vacuum dried at 120 ^° C. to prepare a positive electrode.

The prepared positive electrode and the lithium foil as counter electrodes, and a porous polyethylene membrane

(Celgard 2300, thickness: 25, manufactured by Celgard ELC) as a separator, and a liquid electrolyte in which LiPF ₆ is dissolved at a concentration of 1.2 M in an ethylene carbonate and ethyl methyl carbonate in a volume ratio of 3: 7. Coin half cells were prepared according to commonly known manufacturing processes.

Example 5: Fabrication of Lithium Secondary Battery

The super-active material and the conductive material for the lithium secondary battery prepared in Example 2 were super-

Polyvinylidene fluoride (PVdF) was mixed with P and a binder in a weight ratio of 85: 7.5: 7.5, respectively, to prepare a positive electrode active material layer composition. The positive electrode active material layer composition was uniformly applied to an aluminum foil having a thickness of 20, and vacuum dried at 120 ^° C. to prepare a positive electrode.

The prepared positive electrode and the lithium foil are used as counter electrodes, and the porous polyethylene membrane

(Celgard 2300, thickness: 25 kPa, manufactured by Salgard ELC) is a liquid electrolyte solution in which LiPF ₆ is dissolved at a concentration of 1 M in a solvent in which ethylene carbonate and ethyl metal carbonate are mixed at a volume ratio of 3: 7. Coin half cell was prepared according to a commonly known manufacturing process.

Example 6 Fabrication of a Lithium Secondary Battery

<211> Super- as the positive electrode active material and conductive material for a lithium secondary battery prepared in Example 3

Polyvinylidene fluoride (PVdF) was mixed with P and a binder in a weight ratio of 85: 7.5: 7.5, respectively, to prepare a positive electrode active material layer composition. The positive electrode active material layer composition 20 Uniformly coated on aluminum foil having a thickness, was prepared and a positive electrode was vacuum dried at 120 ^° C.

The prepared anode and the lithium foil as counter electrodes, and a porous polyethylene membrane

(Celgard 2300, two: 25 / m, manufactured by Celgard ELC) as a separator, a liquid electrolyte dissolved in LiPF ^ 1.2M in a solvent mixed with ethylene carbonate and ethylmethyl carbonate in a volume ratio of 3: 7 Coin half cell was prepared according to a commonly known manufacturing process.

Comparative Example 1: Preparation of Positive Electrode Active Material for Lithium Secondary Battery

<2i4> 4L continuous stirred tank reactor (CSTR) (capacity

4L, the output of the rotary motor of more than 90W) FeS0 ₄ · 7¾0, ¾P0 ₄ and NH ₄ 0H was added in a molar ratio of 3: 2: 6 and reacted at pH 7 conditions. The FeS0 ₄ - the 7¾0 was used so that the molar concentration of 2.2 M. The internal temperature of the reaction vessel was stirred at 1000 rpm while maintaining at 55 ^° C. After stirring for 12 hours, a micro-sized spherical active material precursor Fe ₃ (P0 ₄ ) ₂ · xH ₂ 0 was prepared.

Subsequently, the active material precursor was filtered by filtration with a vacuum pump, and then dried at 70 ^° C. for 24 hours under vacuum.

Subsequently, heat treatment was performed at 550 ^° C. for 15 hours under a reducing atmosphere to obtain iron phosphate.

Subsequently, pitch is increased with respect to 100 parts by weight of the iron phosphate to the iron phosphate.

(pitch) Carbon was mixed to 2 parts by weight and stirred.

Subsequently, the iron phosphate was mixed with lithium phosphate (Li ₃ P0 ₄ ) in a molar ratio of 1: 1, and heated to 750 ^° C. at a temperature increase rate of 5 ^° C./min, followed by firing for 15 hours. And the positive electrode active material for olivine type LiFePO ₄ lithium secondary battery containing a carbon coating layer was obtained.

Comparative Example 2: Preparation of Positive Electrode Active Material for Lithium Secondary Battery

<220> 4L continuous stirred tank reactor (CSTR) (capacity

MnSO ^ 5¾0, H ₃ P0 ₄ and NH ₄ 0H were added at a molar ratio of 3: 2 to 4L, and the output of the rotary motor was greater than 90W. At this time, MnS0 ₄ · 5¾0 was used to have a molar concentration of 2.2 M-. The internal temperature of the reaction vessel was stirred at 1000 rpm while maintaining at 55 ^° C. 12 by time stirring, the active material precursor Μη ₃ (Ρ0 ₄₎ the size of the micro sphere _2, was prepared xH ₂ 0. <221>. Subsequently, the active material precursor was filtered by filtration with a vacuum pump, and then dried at 70 ^° C. for 24 hours under vacuum.

Subsequently, heat treatment was performed at 550 ^° C. for 15 hours under a reducing atmosphere to obtain manganese phosphate.

Subsequently, pitch is increased with respect to 100 parts by weight of the manganese phosphate to the manganese phosphate.

(pitch) Carbon was mixed to 2 parts by weight and stirred. ·

The manganese phosphate was then mixed with lithium phosphate (Li ₃ P0 ₄ ) in a molar ratio of 1: 1. And, after heating up to 75CTC at a temperature increase rate of 5 ^° C / min, and calcined for 15 hours, to obtain a positive electrode active material for the Liribin type LiMnP0 ₄ lithium secondary battery containing a carbon coating layer.

Comparative Example 3: Preparation of Positive Electrode Active Material for Lithium Secondary Battery

Fill a 4 L continuous stirred tank reactor (CSTR) (capacity 4 L, 90 W or more of the rotary motor) with 2 L of ethanol and 650 mL of H ₃ P0 ₄ and stir.

In another beaker, Mn (N0 ₃ ) ₂ · 4¾0 and Fe (N0 ₃ ) ₃ · 9¾0 were mixed in a molar ratio of 85:15, dissolved in 1 L of ethanol, and then added to the 4L continuous stirred tank reactor (CSTR). Input. This was followed by stirring at 1000 rpm while maintaining the internal temperature of the 4L continuous stirred tank reactor (CSTR) at 40 ^° C. After stirring for 5 hours, the micro-sized spherical active material precursor Mn ₀ . ₈₅ Fe ₀ . ₁₅ P0 ₄ ^■ x¾0 was prepared.

<228> was then filtered to filter the active material precursor with a vacuum pump, and dried for 24 hours at 70 ^° C under vacuum minutes crisis.

Subsequently, heat treatment was performed at 500 ^° C. for 1 hour in an air atmosphere to obtain manganese iron phosphate.

Subsequently, pitch carbon was mixed at 2 parts by weight with respect to 100 parts by weight of the manganese iron phosphate and stirred with the manganese iron phosphate.

Subsequently, the manganese iron phosphate is mixed with lithium carbonate (Li ₂ CO ₃ ) in a molar ratio of 1: 1, and heated to 700 ^° C. at a temperature increase rate of 5 ^° C./minute, followed by firing for 15 hours. , Olivine-type LiMn ₀ containing a carbon coating layer. ₈₅ Fe ₀ . _The positive electrode active material for 15PO ₄ lithium secondary batteries was obtained.

Comparative Example 4: Preparation of Positive Electrode Active Material for Lithium Secondary Battery

<233> 4 L continuous stirred tank reactor (CSTR) (capacity

4L, 90W or more of the output of the rotary motor) NiS0 ₄ · 6H ₂ 0, H ₃ P0 ₄ and NH ₄ 0H in a 3: 2: 6 molar ratio It was added and reacted at pH 7 conditions. At this time, the NiS0 ₄ .6¾0 was used so that the molar concentration of 2.2 M. The internal silver degree of the reaction was stirred at 1000 rpm while maintaining at 55 ^° C. After stirring for 12 hours, a micro-sized spherical active material precursor Ni ₃ (P0 ₄ ) ₂ · x¾0 was synthesized.

Subsequently, nickel phosphate was obtained by heat treatment ^at 550 ^° C. for 15 hours under a reducing atmosphere.

<236> followed. _. ， Pitch based on 100 parts by weight of the nickel phosphate to the nickel phosphate

(pitch) A carbon coating layer was formed on the surface of the nickel phosphate by mixing and stirring carbon at 2 parts by weight.

Subsequently, the nickel phosphate having the carbon coating layer formed thereon is lithium phosphate.

(Li ₃ P0 ₄ ) is mixed with a molar ratio of 1: 1, the temperature is raised to 750 ^° C at a temperature increase rate of 5 ^° C / min, and then fired for 10 hours, the positive electrode active material for the Li-Libin LiNiP0 ₄ lithium secondary battery Got

Comparative Example 5: Preparation of Positive Electrode Active Material for Lithium Secondary Battery

<239> 4 L continuous stirred tank reactor (CSTR) (capacity

CoS0 ₄ · 7¾0, H ₃ P0 ₄ and NH ₄ 0H were added at 4L, and the output of the rotating motor of 90 W or more in a molar ratio of 3: 2: 6 and reacted at pH 7 conditions. CoS0 ₄ · 7¾0 was used at a molar concentration of 2.2 M. The internal temperature of the semi-unggi is was agitated at 1000 rpm and kept at 55 ^° C. After stirring for 12 hours, a micro-sized spherical active material precursor Co ₃ (P0 ₄ ) ₂ · x¾0 was synthesized.

Subsequently, the active material precursor was filtered by filtration with a vacuum pump, and then dried at 70 ^° C. for 24 hours under vacuum separation.

Subsequently, heat treatment was performed at 55 CTC for 15 hours under a reducing atmosphere to obtain cobalt phosphate.

Subsequently, a carbon coating layer was formed on the surface of the cobalt phosphate by mixing and stirring pitch carbon at 2 parts by weight with respect to 100 parts by weight of the cobalt phosphate.

Next, the cobalt phosphate having the carbon coating layer formed thereon is lithium phosphate: (Li ₃ P0 ₄ ) and a molar ratio of 1: 1, and after heating up to 750 ^° C at a rate of 5 ^° C / min, 15. Fired for a time, and scored up ^'LiCoP0 ₄ cathode active material for a lithium secondary battery of binhyeong.

Comparative Example 6: Fabrication of Lithium Secondary Battery

<245> The super-active material and the conductive material for a lithium secondary battery prepared in Comparative Example 1-

Polyvinylidene fluoride (PVdF) was mixed with P and a binder in a weight ratio of 85: 7.5: 7.5, respectively, to prepare a positive electrode active material layer composition. The positive electrode coating composition was coated uniformly on an aluminum foil of 20 thickness, and was manufactured with the ^"positive electrode was vacuum dried at 120 ^° C. ..

(Celgard 2300, thickness: manufactured by Celgard ELC) as a separator, and a liquid electrolyte in which LiPF ₆ is dissolved at a concentration of 1.2 M in ethylene carbonate and ethyl methyl carbonate in a volume ratio of 3: 7. Coin half cells were prepared according to commonly known manufacturing processes.

Comparative Example 7: Fabrication of Lithium Secondary Battery

The super-active material and the conductive material for the lithium secondary battery prepared in Comparative Example 2 were super-

Polyvinylidene fluoride (PVdF) was mixed with P and a binder in a weight ratio of 85: 7.5: 7.5, respectively, to prepare a positive electrode active material layer composition. The positive electrode active material layer composition was uniformly applied to 20 μM thick aluminum foil, and vacuum dried at 120 ^° C. to prepare a positive electrode.

<249> The anode and the lithium foil prepared as the counter electrode, a porous polyethylene membrane

(Celgard 2300, thickness: 25 / zm, manufactured by Selgard ELC) as a separator, and a liquid in which LiPF ₆ is dissolved in a concentration of 1.2 M in an ethylene carbonate and ethyl methyl carbonate in a volume ratio of 3: 7. The coin half cell was prepared using the electrolyte according to a commonly known manufacturing process.

Comparative Example 8: Fabrication of Lithium Secondary Battery

<251> Super- as a positive electrode active material and a conductive material for a lithium secondary battery prepared in Comparative Example 3

Polyvinylidene fluoride (PVdF) was mixed with P and a binder in a weight ratio of 85: 7.5: 7.5, respectively, to prepare a positive electrode active material layer composition. The positive electrode active material layer composition was uniformly coated on a 20-thick aluminum foil, and vacuum dried at 120 ^° C. to prepare a positive electrode. The prepared positive electrode and the lithium foil as counter electrodes, and a porous polyethylene membrane

(Celgard 2300, thickness: 25, manufactured by Salgard ELC), a liquid electrolyte in which LiPF ₆ is dissolved at a concentration of 1 M in a solvent in which ethylene carbonate and ethyl methyl carbonate are mixed in a volume ratio of 3: 7. According to the known manufacturing process. Coin half cell was prepared.

Comparative Example 9: Fabrication of Lithium Secondary Battery

<254> The super-active material and the conductive material for a lithium secondary battery prepared in Comparative Example 4-

Polyvinylidene fluoride (PVdF) was mixed with P and a binder in a weight ratio of 85: 7.5: 7.5, respectively, to prepare a positive electrode active material layer composition. The positive electrode active material layer composition was uniformly coated on an aluminum foil having a thickness of 20 / zm, and vacuum dried at 120 ^° C. to prepare a positive electrode.

The positive electrode and the lithium foil prepared as the counter electrode, and the porous polyethylene membrane

^• (Celgard 2300, thickness: 25, manufactured by Celgard ELC) as a separator, and a liquid electrolyte in which LiPF ₆ is dissolved in 1.2 M concentration in a mixture of ethylene carbonate and ethyl methyl carbonate in a volume ratio of 3: 7. The coin half cell was prepared according to a commonly known manufacturing process using

Comparative Example 10 Fabrication of a Lithium Secondary Battery

The superchar with a positive electrode active material and a conductive material for a lithium secondary battery prepared in Comparative Example 5

Polyvinylidene fluoride (PVdF) was mixed with P and a binder in a weight ratio of 85: 7.5: 7.5, respectively, to prepare a positive electrode active material layer composition. The positive electrode active material layer composition was uniformly applied to a 20 _m thick aluminum foil, and vacuum dried at 120 ^° C. to prepare a positive electrode.

(Celgard 2300, thickness: 2 m, the cell-garde El elssi agent) to a separator, and ethylene car carbonate and ethyl methyl carbonate 3: dissolved road 2 M perch: 7 a common combined LiPF ₆ in a solvent in a volume ratio 1 of Coin half cells were prepared using a liquid electrolyte according to a commonly known manufacturing process.

Test Example 1 Tap Density Measurement

Each of the positive electrode active materials for lithium secondary batteries prepared in Examples 1 to 3 and Comparative Examples 1 to 5 was stroked 500 times using a 10 ml measuring cylinder to measure the map density. <26i><Comparison of Example 1, Example 2 and Comparative Examples 1 to 3>

^■ The cathode active material for a lithium secondary battery prepared in Example 1 has a tap density of 1.5 g / cm ^{3, and} the cathode active material for a lithium secondary battery prepared in Example 2 has a lap density of 1.5 g / cm ³ . The positive electrode active material for lithium secondary batteries prepared in Comparative Example 1 has a tap density of 1.4 g / cm ³ , the positive electrode active material for lithium secondary batteries prepared in Comparative Example 2 has a tap density of 1.2 g / cm ³ , The cathode active material for a lithium secondary battery prepared in Comparative Example 3 has a wrap density of 1.2 g / cm ³ .

From this, it can be seen that the tap densities of the positive electrode active materials for lithium secondary batteries of Examples 1 and 2 are greater than the tap densities of the positive electrode active materials for lithium secondary batteries of Comparative Examples 1 to 3.

The cathode active material for a lithium secondary battery prepared in Example 3 has a tap density of 1.5 g / cm ³ , and the cathode active material for a lithium secondary battery prepared in Comparative Example 4 has a tap density of 1.4 g / cm ³ . , The cathode active material for a lithium secondary battery manufactured in Comparative Example 5 has a tap density of 1.2 g / cm ³ .

<266> From this, the tap density of the positive electrode active material for lithium secondary batteries of Example 3 is Comparative Example 4

And it can confirm that it is larger than the tap density of the positive electrode active material for lithium secondary batteries of 5. Test Example 2: Seaming electron microscope (SEM) photography and energy dispersive X-ray (EDX) analysis

After sampling the core-shell precursor prepared in Examples 1 to 3 and the cathode active material for a lithium secondary battery, and the active material precursor prepared in Comparative Examples 1 to 5 on a carbon tape, respectively, platinum (Pt) plasma Coating was taken by SEM and energy dispersive X-ray analysis was performed.

<269> scanning electron microscope (SEM) JSM 6400 (JEOL)

Company) was used.

<27i> A scanning electron microscope (SEM) photograph at 3,000 times magnification of a portion of the core-shell precursor prepared in Example 1 is shown in FIG. 2, and a scanning electron microscope (SEM) photograph at 30,000 times magnification is shown in FIG. Shown in

In addition, the energy-dispersive X-ray (EDX) of the core-shell precursor prepared in Example 1 Analytical data is shown in FIG. 4.

As shown in Figure 2 and 3, the core-shell precursor prepared in Example 1 is. The surface of the core is surrounded by spherical particles, and it can be seen that the core-shell structure is formed.

In addition, as shown in Figure 4, the core-shell precursor prepared in Example 1

It can be seen that it contains both Mn and Fe.

Therefore, referring to FIGS. 2 to 4, the cathode active material for a lithium secondary battery prepared by heat-treating and firing the core-shell precursor prepared in Example 1 is LiMnP0 ₄ (core) −

It can be expected to have a LiFePO ₄ (shell) structure.

A scanning electron microscope (SEM) photograph at 12, 000 times magnification of a portion of the core-shell precursor prepared in Example 2 is shown in FIG. 5, and a part of the cathode active material for a lithium secondary battery prepared in Example 2 The scanning electron microscope (SEM) photograph which enlarged 15,000 times is shown in FIG.

<277> FIG. 5 and described above, in the embodiment ^2, manufactured core shown in Figure 6-shell precursor and Lyrium secondary battery positive electrode active material core - can confirm that it is formed as a shell structure. As a result, the cathode active material for a lithium secondary battery prepared in Example 2 was LiMn ₀ . ₈₅ Fe ₀ . ₁₅ P0 ₄ (core) —You can expect to have a LiFeP0 ₄ (shell) structure.

On the other hand, a scanning electron micrograph in which a portion of the active material precursor prepared in Comparative Example 2 is enlarged 4,000 times is shown in FIG. 7, and the scanning electron microscope is enlarged 30,000 times.

(SEM) photo is shown in FIG.

In addition, the energy dispersive X-ray (EDX) of the active material precursor prepared in Comparative Example 2

Analytical data is shown in FIG. 9.

As shown in FIG. 7 and FIG. 8, it can be seen that the active material precursor prepared in Comparative Example 2 is formed of micron size secondary particles in which plate-shaped primary particles are aggregated.

In addition, as shown in Figure 9, the active material precursor prepared in Comparative Example 2

It can be confirmed that it contains Mn.

Thus, referring to FIGS. 7 to 9, it can be predicted that the active material precursor prepared in Comparative Example 2 has a LiMnP0 ₄ particle structure.

<284>. Scanning electron microscope (SEM) of the cross section of the core-shell precursor prepared in Example 3 The photo is shown in FIG.

In addition, energy dispersive X-ray (EDX) analysis data for points A and B of FIG. 10 are shown in FIGS. 11 and 12, respectively.

10, 11 and 12, the core manufactured in Example 3

It can be seen that the shell precursor is formed of a core-shell structure comprising a core comprising Ni and a shell comprising Co.

Therefore, referring to FIGS. 10, 11, and 12, the core manufactured in Example 3 is described.

The cathode active material for a lithium secondary battery prepared by heat-treating and firing a shell precursor may be predicted to have a UNiP0 ₄ (core) -LiCoP0 ₄ (shell) structure.

On the other hand, a scanning electron microscope of the cross section of the active material precursor prepared in Comparative Example 4

(SEM) photograph is shown in FIG.

In addition, energy dispersive X-ray (EDX) analysis data for points C and D of FIG. 13 are shown in FIGS. 14 and 15, respectively.

13, 14 and 15, it can be seen that the active material precursor prepared in Comparative Example 4 is formed in a single particle structure containing Ni. Therefore, referring to FIGS. 13, 14, and 15, the active material prepared in Comparative Example 4 may have a LiNiP0 ₄ particle structure.

Test Example 3: Measurement of initial charge capacity, initial discharge capacity and keg efficiency

30 coin halves prepared in Example 4, Comparative Example 6 and Comparative Example 7

Charge and discharge was performed once at 0.05 C-rate at ^° C, 2.7 V to 4.5 V, and the initial charge capacity, initial discharge capacity, and keg efficiency were measured.

FIG. 16 shows a single layer discharge graph of the coin half cell prepared in Example 4. FIG.

As shown in FIG. 16, the coin half-sal prepared in Example 4 exhibited an initial layer capacity of 153 mAh / g and an initial discharge capacity of 152 mAh / g, resulting in a 99.3% kinematic efficiency.

17 shows a single layer discharge graph of the coin half sal prepared in Comparative Example 7.

As shown in FIG. 17, the coin half cell prepared in Comparative Example 7 exhibited an initial charge capacity of 162 mAh / g and an initial discharge capacity of 145 mAh / g, representing 89.5%. Represents the cooler efficiency.

<299>. Thus, the coin half cell prepared in Example 4 had a smaller initial charge capacity than the coin half cell prepared in Comparative Example 7, but had better initial discharge capacity and flow efficiency than the coin half cell prepared in Comparative Example 7. can confirm.

<300><Comparison of Example 5 and Comparative Example 8>^'

<30i> The coin half cells prepared in Example 5 and Comparative Example 8 were subjected to one layer discharge at 20 C-rate at 30 ^° C. and 2.7 V to 4.5 V, respectively, for initial charge capacity and initial discharge capacity. And the coolant efficiency was measured.

FIG. 18 shows one time charge and discharge graphs of the coin half cells prepared in Example 5 and Comparative Example 8. FIG.

18, the coin half cell prepared in Example 5 exhibited an initial layer capacity of 170 mAh / g and an initial discharge capacity of 154 mAh / g, indicating a keg efficiency of 90.6%. The coin half cell prepared in Comparative Example 8 exhibited an initial layer capacity of 162 mAh / g and an initial discharge capacity of 142 mAh / g, resulting in a cleavage efficiency of 87.7%.

As a result, it can be seen that the coin half cell manufactured in Example 5 had better initial layer capacitance and initial discharge capacity matching efficiency than the coin half cell prepared in Comparative Example 8.

<305> Comparison of Example 6, Comparative Example 9 and Comparative Example 10>

30 coin halves prepared in Example 6, Comparative Example 9 and Comparative Example 10, respectively;

^The charging and discharging was performed once at 0.05 C-rate (7.5 mA / g) at 3.0 ^° C. to 3.0 V, and the initial charge capacity, initial discharge capacity, and keg efficiency were measured.

19 shows a single layer discharge graph of the coin half cell prepared in Example 6 above. The coin half cell prepared in Example 6 exhibited an initial layer capacity of 109.6 mAh / g and an initial discharge capacity of 63.2 mAh / g, resulting in a kinematic efficiency of about 58%.

20 shows a graph of one time charge and discharge of the coin half sal prepared in Comparative Example 9. The coin half cell prepared in Comparative Example 9 exhibited an initial charge capacity of 99.5 mAh / g and an initial discharge capacity of 14.4 mAh / g, indicating a kinematic efficiency of about 14%.

As a result, it was confirmed that the coin half cell prepared in Example 6 had better initial layer capacity, initial discharge capacity, and cooler efficiency than the coin half cell prepared in Comparative Example 9. can do.

Test Example 4: Cycle Life Characteristics ^''

<3ΐι> <Comparison of Example 4, Comparative Example 6 and Comparative Example 7>

The coin half cells prepared in Example 4, Comparative Example 6 and Comparative Example 7 were each 2.7V.

From -4.5V, the change of discharge capacity was measured, performing 50-cycle charge-discharge at 0.05C-rate. Among these, the results of Example 4 and Comparative Example 7 are shown in FIG.

As shown in FIG. 21, after 50 cycles of charge and discharge, the coin half cell of Example 4 showed a capacity retention of about 97%, and the coin half cell of Comparative Example 7 had a capacity of about 89%. Retention rate is shown.

Therefore, the coin half cell prepared in Example 4 achieves higher capacity than the coin half cell prepared in Comparative Example 7, but it can be confirmed that the coin half cell has better life characteristics than the coin half cell prepared in Comparative Example 7. have.

<315> <Comparison of Example 5 and Comparative Example 8>

Each coin half cell prepared in Example 5 and Comparative Example 8 was 2.7 V to 4.5 V, respectively.

The change in the discharge capacity was measured while performing 50 cycle layer discharge at a temperature of about 55 ^° C. at 0.2 C-rate. The results of Example 5 and Comparative Example 8 are shown in FIG. 22.

22, after 50 cycles of layer discharge, the coin half cell of Example 5 exhibited a capacity retention of about 95.6%, and the coin half sal of Comparative Example 8 was about 81.2%. Capacity retention ratio

Therefore, the coin half cell prepared in Example 5 achieved higher capacity than the coin half cell prepared in Comparative Example 8, but it was confirmed that the coin half cell had better life characteristics than the coin half cell prepared in Comparative Example 8. .

Test Example 5: Evaluation of Thermal Properties

The coin half cells prepared in Examples 4 to 6 and Comparative Examples 6 to 10, respectively, were used.

After charging to 4.5V with 0.5C-rate at 25t :, disassembled in a glove box filled with argon (Ar).

<32i> Differential scanning calorimetry (DSC) was carried out using the Shimadzu DSC-60 (manufactured by Shimadzu) equipment of the disassembled positive electrode plate.

23 shows the results of differential scanning calorimetry (DSC) of Example 4, Comparative Example 6 and Comparative Example 7. FIG. As shown in FIG. 23, it can be confirmed that the calorific value of Example 4 is less than that of Comparative Example 7 and is similar to that of Comparative Example 6. In addition, it can be confirmed that the onset temperature of Example 4 is higher than the exothermic onset of silver in Comparative Example 7 and the exothermic onset of Comparative Example 6 is at a similar level.

As a result, it can be seen that the coin half cell prepared in Example 4 has excellent thermal characteristics.

Although the preferred embodiment of the present invention has been described above, the present invention is not limited thereto, and various modifications and changes can be made within the scope of the claims and the detailed description of the invention and the accompanying drawings. This also belongs to the scope of the present invention.

Claims

[Range of request]

[Claim 1]

A core containing a compound represented by the following formula (1); And

Shell containing a compound represented by the formula (2)

Including;

A material composition of the core and a material composition of the shell are different from each other:

[Formula 1]

Li _x iMl _y iM2 _zl P0 ₄ -wiE _w i

[Formula 2]

Li _x2 M3 _y2 M4 _z2 P0 ₄ - _W 2E _w2

In Chemical Formulas 1 and 2,

Ml, M2, M3 and M4 are the same or different from each other, and each independently Ni, Co, Mn, Fe, Na, Mg, Ca, Ti, V, Cr, Cu, Zn, Ge, Sr, Ag, Ba, Zr , Nb, Mo, Al, Ga, B and combinations thereof,

E is selected from the group consisting of F, S and combinations thereof

0 <xl <l.l, 0 <yl <l, 0 <zl <l, 0 <xl + yl + zl <2.

0 <wl <0.5

'0 <χ2 <1.1, 0 <y2 <l, 0 <ζ2 <1, 0 <x2 + y2 + z2 <2,

0 <w2 <0.5.

[Claim 2]

The method of claim 1,

Wherein Ml and M3 are the same material, M2 and M4 are the same material, xl = x2, yl <y2 and zl> z2 positive electrode active material for a lithium secondary battery.

[Claim 3]

The method of claim 2,

Ml and M3 are selected from the group consisting of Fe, Co, Ni, Mn, and combinations thereof,

Wherein M2 and M4 is selected from the group consisting of Mn, Ni, Co, Fe and combinations thereof Cathode Active Material for Lithium Secondary Battery.

[Claim 4]

The method of claim 1,

Wherein Ml and M3 is a different material from the positive electrode active material for a lithium secondary battery.

[Claim 5]

The method of claim 1,

Wherein M2 and ^" M4 is a material different from each other positive electrode active material for a lithium secondary battery.

[Claim 6]

The method of claim 1,

Ml and M2 are different from each other,

The core has a structure in which the concentration of Ml increases and the concentration of M2 decreases as it moves away from the core of the core.

Ml is selected from the group consisting of Fe, Co, Ni, Mn, and combinations thereof, and M2 is selected from the group consisting of Mn, Ni, Co, Fe, and combinations thereof.

[Claim 7]

The method of claim 1,

The core is a positive electrode active material for a lithium secondary battery having a diameter of 5 / mi to 20.

[Claim 8]

The method of claim 1,

M3 and M4 are different from each other,

The shell has a structure in which the concentration of the M3 increases and the concentration of the M4 decreases away from the interface between the core and the shell.

M3 is selected from the group consisting of Fe, Co, Ni, Mn, and combinations thereof, M4 is selected from the group consisting of Mn, Ni, Co, Fe and combinations thereof.

[Claim 9]

The method of claim 1,

The shell is a cathode active material for a lithium secondary battery having a thickness of 100 nm to 5.

[Claim 10]

The method of claim 1,

The cathode active material for a lithium secondary battery which further comprises a carbon coating layer on the surface of the shell.

[Claim 11]

The method of claim 10,

The carbon coating layer is a lithium secondary battery positive electrode, active material having a thickness of 10 nm to 200 nm.

[Claim 12]

The method of claim 1,

Further comprising an intermediate layer between the core and the shell, the intermediate layer comprises a compound represented by the formula

The material composition of the intermediate layer is different from the material composition of the core and the material composition of the shell positive electrode active material for a lithium secondary battery:

[Formula 3]

Li _x3 M5 _y3 M6 _z3 P0 ₄ - _w3 E _w3

In Chemical Formula 3,

M5 and M6 are the same or different from each other, and each independently Ni, Co, Mn, Fe, Na, Mg, Ca, Ti, V, Cr, Cu, Zn, Ge, Sr, Ag, Ba, Zr, Nb, Mo , Al, Ga, B and combinations thereof,

E is selected from the group consisting of F, S and combinations thereof

0 <x3 <ll, 0 <y3 <l, 0 <ζ3 <1, 0 <x3 + y3 + z3 <2, 0 <w3 <0.5. ί Claim 13]

The method of claim 12,

Ml, M3, and M5 are the same material, and M2, M4, and M6 are the same material, and xl = x2 = x3, yl <y3 <y2 and zl> z3> z2. Active material.

[Claim 14]

In accordance with claim 13,

Ml, M3 and M5 are selected from the group consisting of Fe, Co, Ni, Mn, and combinations thereof,

The M2, the M4 and the M6 is selected from the group consisting of Mn, Ni, Co, Fe and combinations thereof

Cathode active material for lithium secondary battery.

[Claim 15]

The method of claim 12,

The Ml, the M3 and the M5 are each a different material from the positive electrode active material for a lithium secondary battery.

[Claim 16]

The method of claim 12,

The M2, the M4 and the M6 are each a different material from the positive electrode active material for a lithium secondary battery.

[Claim 17]

The method of claim 12,

M5 and M6 are different from each other,

The intermediate layer has a structure in which the concentration of M5 increases and the concentration of M6 decreases as the distance from the core increases.

M5 is selected from the group consisting of Fe, Co, Ni, Mn, and combinations thereof, M6 is selected from the group consisting of Mn, Ni, Co, Fe and combinations thereof.

[Claim 18]

The method of claim 12,

The intermediate layer is a cathode active material for a lithium secondary battery having a thickness of 100 nm to 24 / m.

[Claim 19]

The method of claim 1 wherein ^"

The positive electrode active material for lithium secondary batteries is a lithium secondary battery positive electrode active material having a diameter of 5 kW to 25.

[Claim 20]

The method of claim 1,

The positive electrode active material for lithium secondary batteries is a positive electrode active material for lithium secondary batteries having a tap density of 1 g / cm ³ to 2 g / cm ³ .

[Claim 21]

Mixing the Ml source, M2 source and phosphoric acid source to form a core precursor;

Mixing the core precursor with an M3 source, an M4 source, and a phosphoric acid source to form a core-shell precursor comprising a shell precursor formed on the surface of the core precursor;

Heat treating the core-shell precursor to form a core-shell composite; And mixing the core-shell composite with a lithium source and firing

Including

Ml, M2, M3 and M4 are the same or different from each other, and each independently Ni, Co, Mn, Fe, Na, Mg, Ca, Ti, V, Cr, 'Cu, Zn, Ge, Sr, Ag, Ba, Zr, Nb, Mo, Al, Ga, B and a method for producing a positive electrode active material for a lithium secondary battery that is selected from the group consisting of these. [Claim 22]

The method of claim 21

The M1 source, the M2 source, the M3 source and the M4 source are Ml, M2, M3 and M4 sulfur oxides, nitrates, acetates, hydroxides, chlorides, oxalates, fluorides, carbonates or combinations thereof Method for producing a cathode active material for a lithium secondary battery comprising a.

[Claim 23]

The method of claim 21,

The source of phosphoric acid is phosphoric acid (H ₃ P0 ₄ ), diammonium phosphate ((NH ₄ ) ₂ HP0 ₄ ), ammonium phosphate trihydrate ((ΝΗ ₄ ) ₃ Ρ0 ₄ · 3¾0), metaphosphoric acid, Orthophosphoric acid

(orthophosphoric acid), ammonium dihydrogen phosphate (NH4¾P0 ₄ ) or a combination thereof, a method for producing a positive electrode active material for a lithium secondary battery.

[Claim 24]

22. The method of claim 21, ^'wherein the lithium source may be lithium phosphate (Li ₃ P0 _4), Lyrium nitrate (LiN0 _3), lithium acetate (LiCH ₃ C00H), lithium carbonate (Li ₂ C0 _3), lithium hydroxide (LiOH), Lyrium die hydrogen phosphate (Li¾P0 ₄₎ or a lithium secondary battery production method of the positive electrode active material comprises a combination of the two.

[Claim 25]

The method of claim 21,

The heat treatment is carried out at a temperature of 3001: to 700 ^° C. A method for producing a cathode active material for a lithium secondary battery.

[Claim 26]

The method of claim 21,

The firing is performed at a temperature of 600 ^° C to 800 ^° C method for producing a positive electrode active material for a lithium secondary battery. [Claim 27]

The method of claim 21,

After the forming of the core-shell composite, further comprising the step of forming a carbon coating layer on the surface of the core-shell composite.

[Claim] _. 28】

The method of claim 21,

After forming the core precursor, further comprising mixing the core precursor with an M5 source, an M6 source and a phosphoric acid source to form an interlayer precursor on the surface of the core precursor;

M5 and M6 are the same or different from each other, and each independently Ni, Co, Mn, Fe, Na, Mg, Ca, Ti, V, Cr ᅳ Cu, Zn, Ge, Sr, Ag, Ba, Zr, Nb A method for producing a cathode active material for a lithium secondary battery, which is selected from the group consisting of Mo, Al, Ga, B and combinations thereof. ^'

[Claim 29]

The method of claim 28,

The M5 source and the M6 source include sulfur oxides, nitrates, acetates, phosphates, chlorides, oxalates, fluorides, carbonates or combinations thereof of M5 and M6, respectively,

The source of phosphoric acid is phosphoric acid (¾P0 ₄ ), diammonium phosphate ((NH ₄ ) ₂ HP0 ₄ ), ammonium phosphate trihydrate ((NH ₄ ) ₃ P0 ₄ · 3¾0), metaphosphoric acid, orthophosphoric acid

(orthophosphoric acid), this acid ammonium (NH _₄ ¾P0 ₄₎ or the Lyrium method of producing a secondary battery, the positive electrode active material and that is a combination thereof.

[Claim 30]

Mixing the Ml source and the M2 source to form a core precursor;

Mixing the core precursor with an M3 source and an M4 source to form a core-shell precursor comprising a shell precursor formed on the surface of the core precursor; And

Mixing and firing the core-shell precursor with a lithium source and a phosphoric acid source system

Contains'

Ml, M2, M3, and M4 are the same or different from each other, and each independently Ni, Co, Mn, Fe, Na, Mg, Ca, Ti, V, Cr, Cu, Zn, Ge, Sr, Ag , Ba, Zr, Nb, Mo, Al, Ga, B and a method for producing a positive electrode active material for a lithium secondary battery that is selected from the group consisting of these.

[Claim 31]

The method of claim 30,

The core-shell, after the step of forming a ^"precursor, wherein the core-in a lithium secondary battery positive electrode hwalmul query method comprising the step of forming a carbon coating layer further on the surface of the shell precursors.

[Claim 32]

The method of claim 30,

After forming the core precursor, further comprising: mixing the core precursor with an M5 source and an M6 source to form an interlayer precursor on the surface of the core precursor,

M5 and M6 are the same or different from each other, and each independently Ni, Co, Mn, Fe, Na, Mg, Ca, Ti, V, Cr, Cu, Zn, Ge, Sr, Ag, Ba, Zr, Nb A method for producing a cathode active material for a lithium secondary battery, which is selected from the group consisting of Mo, Al, Ga, B and combinations thereof.

[Claim 33]

A positive electrode including a positive electrode active material;

A negative electrode including a negative electrode active material; And

Contains an electrolyte,

The positive electrode active material is a lithium secondary battery that is the positive electrode active material for lithium secondary battery of any one of claims 1 to 20.